Motor vehicles with inflatable tires such as cars, vans, sport utility vehicles, cross over vehicles, light and heavy duty trucks, tractor trailers, buses, commercial delivery vehicles, among other motorized forms of motorized transportation and trailers pulled by such vehicle are conventionally equipped with spare tires. Some spare tires are stored under the vehicle using a tire carrier which includes a tire winch for raising and lowering the spare tire between a raised or stored position and a lowered or accessed position. The winch typically raises and lowers the spare tire using a flexible member such as a cable or cord which is wound and unwound on a lift drum or reel.
Such tire carriers have been subject to failure due to over loading. When the winch is used to raise a tire from the lowered position to the raised position, the user is unable to determine when the tire is properly stored in the raised position. Thus, in order to make sure the tire is properly raised, there is a tendency for the user to continue to exert torque on the lift drum in an attempt to further wind the cable about the drum. This exerts ever-increasing tension on the cable and may cause it to break, resulting in failure of the tire carrier and the tire dropping to the ground.
Torque limiting clutches have been used to prevent rotation of the lift drum once a predetermined maximum stress has been placed on the cable. After the maximum stress has been reached, the application of additional torque results in the clutch overrunning to prevent additional tension from being placed on the cable. While such clutches effectively reduce the number of tire carrier failures, the prior clutches have been expensive to manufacture and require extremely valuable vehicle packaging space. Additionally, such clutches must be substantially redesigned for each specific application depending on tire characteristics such as weight, diameter, and thickness.
Accordingly, there is a need in the art for an improved disk clutch for a tire carrier.